JP2000068561A - Apparatus for conveying elements - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical transmitter which has a light emitting diode and a drive circuit for normal time driving the light emitting diode both mixedly mounted, and furthermore which enables selection of the light emitting diode. SOLUTION: A light emitting diode 32 and an integrated circuit 33 for driving the light emitting diode are mixed by mounted in the package of an optical transmitter 31. The cathode of the light emitting diode 32 is connected to the terminal of a power supply for the light emitting diode to be applied by a constant voltage. Also, the anode is connected to the terminal for a constant current supply, and the light emitting diode is supplied with current from the constant current supply when selecting the light emitting diode. This enables the job of selecting the light emitting diode with the integrated circuit 33 for driving the light emitting diode 33 mounted mixedly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmitter used for communication using, for example, an optical fiber, and more particularly to an optical transmitter suitable for performing a screening test of light emitting diodes.

[0002]

2. Description of the Related Art Light emitting diodes are widely used in various electronic devices such as optical transmitters for inputting an optical signal into an optical fiber. Among them, the reliability of the light emitting diode used for the optical transmitter is particularly important.

Generally, semiconductor devices such as light emitting diodes are
Initially defective products are included with a predetermined probability. Therefore, such defective products are removed through a process of sorting (screening) after manufacturing. In this screening process, first, a predetermined time elapses under conditions more severe than actual use conditions in a state in which the element to be screened is mounted on a heat sink or the like or incorporated in a module. Then, the magnitude of the change in the characteristics of the element before and after that is checked, and if the change is larger than a predetermined width, the element is removed as a rejected product.

[0004] By the way, when selecting a light emitting diode to be incorporated in an optical transmitter, a method of selecting a light emitting diode by itself and connecting a light emitting diode which has been accepted to a drive circuit has been generally used. In order to select a single light emitting diode, for example, Japanese Patent Application Laid-Open No. 10-1607
As shown in the technique for selecting a semiconductor laser described in Japanese Patent Publication No. 85, it is not always necessary to measure the current-light output characteristics, but to measure other characteristics such as the current-voltage characteristics of a light emitting diode. It is also possible.

However, in such a method, even if a defective LED is removed from a light emitting diode manufactured, if the light emitting diode is damaged at the stage of being incorporated into the optical transmitter, the light emitting diode as a finished product will not be damaged. Good products will be mixed. Therefore, it is necessary to perform the sorting twice, and the cost required for the sorting becomes high. In the technique disclosed in Japanese Patent Application Laid-Open No. 4-321288, like a semiconductor laser drive circuit, elements are selected while the drive circuit is connected to the elements. However, in the case of an optical transmitter, such selection cannot be performed. This will be described below.

FIG. 8 shows a state of selecting light emitting diodes. In the optical transmitter 11, a light emitting diode 12 and a light emitting diode driving integrated circuit (LD driving LSI) 13 for driving the light emitting diode 12 are arranged. The optical transmitter 11 is provided with two terminals, a power terminal 14 for a light emitting diode and a power terminal 15 for a drive circuit. When the light-emitting diodes 12 are selected, by driving them at a high temperature, a change in characteristics can be determined in a short time. For this reason, the screening process is performed in a state where the optical transmitter 11 is placed in the constant temperature bath 17. The thermostat 17 is maintained at a predetermined temperature while this step is performed by the control circuit 18. The control circuit 18
During this step, the power supply terminal 1 for the light emitting diode is used.
A predetermined voltage is applied from the constant voltage source 19 to both the power supply terminal 4 and the drive circuit power supply terminal 15, and control is performed so that a predetermined current 21 flows through the light emitting diode 12.

[0007]

In the optical transmitter 11 shown in FIG. 8, the current 21 to be supplied to the light emitting diode 12 at the time of the selection process is set to be larger than a normal value. However, this current value is much larger than the current value at which the LD drive LSI 13 can drive the light emitting diode 12. Therefore, LD driving LSI
13 after hybrid mounting with the light emitting diode 12
Using the driving LSI 13 as it is, the light emitting diode 12
Can not be sorted out. Of course, an LD driving LSI capable of driving the light emitting diode 12 with a large current
It was not economical to use 13 with light emitting diode 12 to make an optical transmitter.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical transmitter in which a light emitting diode and a driving circuit for driving the light emitting diode are mounted in a hybrid manner, and the light emitting diode can be selected.

[0009]

According to the first aspect of the present invention, a light emitting diode is connected between two electrodes of (a) an anode and a cathode of the light emitting diode, and (b) a light emitting diode is driven by driving the light emitting diode. A driving circuit for outputting a signal; (c) a voltage application terminal for a light emitting diode, which is disposed in a package on which the light emitting diode and the driving circuit are mounted and applies a voltage to one electrode of the light emitting diode; The optical transmitter includes a light emitting diode selecting current supply terminal for supplying a current to be flown at the time of screening the light emitting diode to the other electrode of the light emitting diode, which is arranged in the package.

That is, according to the present invention, terminals corresponding to both poles of the light emitting diode are arranged in the package so that the light emitting diode mounted on the package as the optical transmitter can be controlled independently. I decided to do it. 2. The invention according to claim 1, wherein conventionally, it is not possible to control the light-emitting diode independently while the drive circuit is mounted on the package, and only one electrode of the light-emitting diode is connected to the terminal. As a result, the work of sorting the light emitting diodes mounted on the package has become possible.

According to the second aspect of the present invention, (a) a light emitting diode and (b) a light emitting diode connected between two anode and cathode electrodes of the light emitting diode for driving the light emitting diode to output an optical signal. A drive circuit, (c) a light emitting diode voltage application terminal for applying a voltage to one electrode of the light emitting diode, which is disposed on a package on which the light emitting diode and the drive circuit are mounted, and (d) a light emitting diode disposed on the package. A light-emitting diode selection current supply terminal for supplying a current to the other electrode of the diode during the screening of the light-emitting diode, and (e) an electric connection between the light-emitting diode selection current supply terminal and the other electrode of the light-emitting diode. And a switch for turning on and off the optical transmitter.

That is, according to the second aspect of the present invention, a switch for electrically turning on and off between the light emitting diode selecting current supply terminal and the other electrode of the light emitting diode according to the first aspect of the present invention is newly provided. I decided to provide. This is because after the screening of the light-emitting diodes is completed, not only is the light-emitting diode selecting current supply terminal unnecessary, but also it is possible to prevent adverse effects caused by the terminal being in electrical contact with other components or the like. .

According to a third aspect of the present invention, in the first or second aspect of the present invention, the light-emitting diode selecting current supply terminal is arranged on the back surface of the package so as not to protrude from the side surface. Features.

[0014] This is to prevent the adverse effects caused by careless electrical contact of the light emitting diode selection current supply terminal as in the switch according to the second aspect of the present invention. That is, if this electrode is arranged at a position which does not protrude from the rear surface portion and the side surface portion of the package, after the light emitting diode screening is completed and the package is mounted at a predetermined position, the light emitting diode selecting current supply terminal Is hidden in a position that is not accessed from the outside, so that the above-mentioned adverse effects do not occur.

According to the fourth aspect of the present invention, it has been clarified that the one electrode is a cathode and the other electrode is an anode. Depending on the driving method of the optical transmitter, the arrangement of the electrodes may be reversed.

According to a fifth aspect of the present invention, in the optical transmitter according to the first or second aspect, the current supply terminal for selecting a light emitting diode is set in a state where the package is heated to a predetermined temperature in a constant temperature bath. The present invention is characterized in that a predetermined current larger than that in normal use is supplied from a current source. This shows an example of a situation when the selection of the light emitting diodes is performed. Of course, it is also possible to perform screening without placing the package in a thermostat.

According to a sixth aspect of the present invention, in the optical transmitter according to the first or second aspect, the package for heating the light emitting diode is heated to a predetermined temperature in the constant temperature bath at the current supply terminal for the light emitting diode sorting. A constant current source for supplying a predetermined current larger than that in normal use from the constant current source in the connected state is connected, and the control circuit controls the temperature of the constant temperature chamber, the current control of the constant current source, and the light emitting diode. It is characterized in that a constant voltage application control to the application voltage application terminal is executed. This is a more specific example of the selection of the light emitting diode according to the fifth aspect.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.

First Embodiment

FIG. 1 shows the configuration of an optical transmitter according to a first embodiment of the present invention. The optical transmitter 31 according to the present embodiment has a configuration in which a light emitting diode 32 is provided with a light emitting diode driving integrated circuit (LD driving LSI) 33. From the package of the optical transmitter 31, a constant current source terminal 36 is provided in addition to the two terminals of the light emitting diode power terminal 34 and the drive circuit power terminal 35.

FIG. 2 shows an outline of the configuration of an apparatus for selecting (screening) light emitting diodes using the optical transmitter of the present embodiment. The optical transmitter 31 shown in FIG.
Is housed in The temperature Ta of the thermostat 30 is controlled by the control circuit 4.
1. Control circuit 41
Is equipped with a computer equipped with a CPU (Central Processing Unit) (not shown).
Overall control for selecting light emitting diodes is also performed. Therefore, the control circuit 41 includes a constant voltage source 42
And the constant current source 43. The constant voltage source 42 includes a light emitting diode power supply terminal 34 and a drive circuit power supply terminal 3.
5 for applying a drive voltage V. Further, the constant current source 43 is connected to the constant current source terminal 36 to supply the drive current I thereto.

FIG. 3 shows the control contents of the control circuit at the time of the light emitting diode sorting operation. FIG. 6A shows _a change in the temperature Ta of the thermostatic bath 30, and FIG. 6B shows a change in the drive voltage V by the constant voltage source 42. FIG. 3C shows a change in the drive current I. In these figures, the time t ₀ is the start time of the light-emitting diode sorting operation, and the heating of the thermostat 30 has been started. From the time t ₁ when the temperature of the thermostat 30 reaches the predetermined temperature, the time t at which the heating control for selecting the light emitting diodes ends.
_It is kept at a constant screening temperature _Tad up to ₆ .

The control circuit 41 controls the temperature of the thermostat 30 to the screening temperature T _ad and a predetermined time for maintaining the optical transmitter 31 accommodated in the thermostat 30 at the screening temperature T _ad. at the time t ₂ but that has elapsed,
A constant voltage drive start control signal 51 is sent to the constant voltage source. As a result, the driving of the constant voltage source 42 is started,
So applying a driving voltage V _d as a predetermined constant voltage from time t ₃ to the light emitting diode power source terminal 34 driving circuit power supply terminal 35.

The control circuit 41 determines that the constant voltage source 42
T when a predetermined margin time for applying
₄ , a constant current drive start control signal 5
2 to start its driving. Thus, the constant current source 43 rises, from time t ₅ becomes the drive current I _d as desired constant current is supplied to the constant current source terminal 36. Heating control for the selection of light-emitting diodes from time t ₅ to be up to time t ₆ to end is called a light emitting diode screening period 61.

In the light emitting diode screening period 61, the driving voltage _Vd is applied to the anode side of the light emitting diode 32 while the optical transmitter 31 is maintained at the screening temperature _Tad . The drive current I _d in this state flows between the anode and the cathode, the light emitting diode 32 emits light. At this time, the driving voltage V is applied to the light emitting diode driving integrated circuit 33 through the driving circuit power supply terminal 35.
_d is applied to the light emitting diode 3
It is not necessary that 2 be driven.

FIG. 4 shows a main part of the control of the CPU in this embodiment. The computer stores a control program in a storage medium such as a magnetic disk or a ROM (read only memory) (not shown), and the CPU executes the program to control the light emitting diodes 32 for selection. Is performed.

First, the CPU sets the light emitting diode power supply terminal 34 and the drive circuit power supply at a stage before setting the optical transmitter 31 in the constant temperature bath 30 or before setting the temperature after setting the optical transmitter 31 in the constant temperature bath 30. A predetermined voltage is applied to two terminals of the terminal 35. Then, the light emitting diode drive integrated circuit 33 is driven under a normal environment, and the characteristics of the light emitting diode 32 are measured (step S101). next,
CPU starts heating control of the thermostatic chamber 30 from the start time t ₁ of the control for the selection of light-emitting diode 32 (step S102).

The control circuit 41 includes a counter for counting a clock signal therein, and uses this count value to count the timing until the arrival of the subsequent times t ₂ , t ₄ and t _6. Has become. However, depending on the control circuit 41, a time t _{1 at} which the temperature of the thermostat 30 reaches a predetermined temperature is detected by a sensor (not shown), and a time t ₂ from the time when the temperature of the optical transmitter 31 is also detected to be constant. May be set. In the case of this embodiment, since control is performed only by the timer circuit using the counter, although the time until the end of the screening is slightly longer, there is an advantage that the control is simplified.

When the CPU monitors the count value and determines that the time t ₂ has come (step S103: Y),
A constant voltage drive start control signal 51 is sent to the constant voltage source 42 (step S104). Thereby, the constant voltage source 4
2 starts driving. Further the CPU Once you have determined that the time t ₄ monitors the count value has been reached (step S
105: Y), sends the constant current drive start control signal 52 to the constant current source 43 to start the drive (step S106). Then, the CPU monitors the count value in the same manner and determines that the time t ₆ has arrived (step S5).
107: Y), the energization of the thermostat 30 is stopped, and the driving of the constant voltage source 42 and the constant current source 43 is stopped (step S108).

Thereafter, the CPU in the control circuit 41 takes out the optical transmitter 31 from the thermostatic chamber 30 or sets the optical transmitter 31 in the thermostatic chamber 3.
After setting the temperature to 0, the temperature of the light-emitting diode power supply terminal 34 and the drive circuit power supply terminal 35
A predetermined voltage is applied to the two terminals. Then, the light emitting diode drive integrated circuit 33 is driven under a normal environment,
The characteristics are measured (Step S109). Then, the obtained measured value is compared with the measured value obtained earlier in step S101 to determine whether or not the light emitting diode 32 of the optical transmitter 31 is an acceptable product (step S101).
110). The criterion for selecting the light emitting diodes 32 is not directly related to the present invention, and a description thereof will be omitted.

Second Embodiment

FIG. 5 shows a state in which the optical transmitter according to the second embodiment of the present invention is set in an apparatus for selecting the same. The same parts as those in FIG. 2 in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

The optical transmitter 71 of the second embodiment comprises a cathode of the light emitting diode 32 and the light emitting diode driving integrated circuit 3.
The connection point 72 with the drive terminal 3 and the constant current source terminal 36 are separated, and a switch 73 is connected between them. The switch 73 has a mechanical contact such as a dip switch, and can be turned on and off by an operator. Of course, depending on the optical transmitter, a new terminal for switch control and a switch drive circuit are provided to control the switch open / close control signal that is turned on during the light emitting diode screening period 61 (see FIG. 3) at the former terminal. It may be supplied from the circuit 41. In this case, power is also supplied from the constant voltage source 42 to the switch driving circuit.

The optical transmitter 71 of the second embodiment turns on the switch 73 for at least the light emitting diode screening period 61 from the time when the optical transmitter 71 is housed in the thermostat 30 to connect the connection point 72 and the constant current source terminal 36. The connection between them is conducted. The operation in this state is the same as that of the first embodiment. After the selection of the light emitting diodes 32 is completed, the switch 73 is turned off, and the connection between the connection point 72 and the constant current source terminal 36 is turned off. Thus, the constant current source terminal 36 of the optical transmitter 71 is completely disconnected from the internal circuit in a normal use state. Therefore, even if a voltage is improperly applied to the constant current source terminal 36 or a state where the voltage is grounded does not occur, there is no inconvenience such as damage to the optical transmitter 71 itself. Therefore, the safety and reliability of the optical transmitter 71 can be improved.

Third Embodiment

FIG. 6 shows the rear surface of the optical transmitter according to the third embodiment of the present invention. The optical transmitter 81 of this embodiment has a plurality of terminals 83 projecting from the left and right sides of the bottom of the package body 82. At a substantially central portion of the bottom of the package body 82, a constant current source terminal 84 is arranged as a pad provided on the back surface.

FIG. 7 is a sectional view showing a state where the optical transmitter is cut in the AA direction of FIG. In FIG. 7, the same portions as those in FIGS. 2 and 5 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. In the optical transmitter 81, the light emitting diode 32 and the light emitting diode driving integrated circuit 33 are mixedly mounted on the upper part of the substrate constituting the package body. The package body 82 is sealed by a lid 85. An optical fiber 86 is optically coupled to the light emitting diode 32, and an optical signal is transmitted to the outside via the optical fiber 86. A connection point 72 between the cathode of the light emitting diode 32 and the drive terminal of the light emitting diode drive integrated circuit 33 is electrically connected to a constant current source terminal 84 via a through hole 87.

In the optical transmitter 81 having such a configuration, the constant current source terminal 84 is connected to the constant current source 43 shown in FIG. 1 in the step of selecting the light emitting diodes 32. To do this,
For example, the constant current source terminal 84 is provided at a predetermined position where the optical transmitter 81 is disposed in the constant temperature chamber 30 described in the first embodiment.
A terminal for connecting to the terminal may be provided. The optical transmitter 81 that has passed the selection of the light emitting diodes 32 has its rear side fixed to a predetermined position on another substrate or the like. This allows
The terminal 84 for the constant current source is hidden in a position where an operator or an electric component cannot easily touch the optical transmitter 81.
Security and reliability can be ensured.

In the first embodiment of the present invention, the terminal corresponding to the constant current source terminal 84 in the third embodiment is realized as the terminal 83 in the second embodiment. Therefore, there is a danger that a worker or an electric component may touch the constant current source terminal 84. In order to reduce such a danger, it is effective to cut the corresponding terminal or to insert an insulating tube into the terminal.

In the embodiment, the constant voltage is applied to the cathode side of the light emitting diode. On the contrary, the present invention can be applied to an optical transmitter in which the constant voltage is applied to the anode side. Further, in the embodiment, only the light emitting diode and the light emitting diode driving integrated circuit are mounted on the package. However, it is obvious that the present invention can be applied to a case where other circuits are further mounted.

[0042]

As described above, according to the first aspect of the present invention, both poles of the light emitting diode can be controlled so that the light emitting diode mounted on the package as an optical transmitter can be controlled independently. Terminals corresponding to the above are arranged on the package. Therefore, the light emitting diode can be driven even when the driving circuit of the package stops operating.

According to the second aspect of the invention, the same effect as that of the first aspect of the invention can be obtained, and furthermore, the ON / OFF state is provided between the light emitting diode selecting current supply terminal and the electrode of the light emitting diode. A switch is provided to prevent the adverse effects of this terminal coming into electrical contact with other parts after the screening of the light emitting diode is completed, regardless of the situation in which the package is placed in the device, and The reliability of the vessel can be improved.

According to the third aspect of the present invention, the same effects as those of the first and second aspects of the present invention can be obtained. In addition, the light emitting diode is provided at a position on the rear surface of the package and not protruding from the side surface. Since the current supply terminal for selection is placed, after placing the package on any member, it is possible to prevent the harmful effects of this terminal coming into electrical contact with other parts, etc., and improve the reliability of the optical transmitter. Moreover, since there is no need to use a switch, there is also an effect that the price of the apparatus can be suppressed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a configuration of an optical transmitter according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an apparatus configuration in a case where a light emitting diode is selected using the optical transmitter of the first embodiment.

FIG. 3 is an explanatory diagram showing control contents of a control circuit at the time of a light emitting diode sorting operation in the first embodiment.

FIG. 4 is a flowchart showing a main part of control of a CPU in the first embodiment.

FIG. 5 is a schematic configuration diagram showing a state where an optical transmitter according to a second embodiment of the present invention is set in an apparatus for selecting the optical transmitter.

FIG. 6 is a rear view of an optical transmitter according to a third embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a state where the optical transmitter is cut in the AA direction of FIG. 6;

FIG. 8 is a schematic configuration diagram showing an outline of a conventional device configuration for selecting light emitting diodes.

[Explanation of symbols]

 Reference Signs List 30 constant temperature bath 31, 71, 81 optical transmitter 32 light emitting diode 33 light emitting diode drive integrated circuit (LD drive LSI) 34 power supply terminal for light emitting diode 35 power supply terminal for drive circuit 36 terminal for constant current source 41 control circuit 42 constant voltage source 43 Constant Current Source 61 Light Emitting Diode Screening Period 73 Switch 84 Constant Current Source Terminal 87 Through Hole

Claims (6)

[Claims] 1. A light emitting diode, a driving circuit connected between two electrodes of an anode and a cathode of the light emitting diode for driving the light emitting diode to output an optical signal, and mounting the light emitting diode and the driving circuit A voltage applying terminal for a light emitting diode, which is arranged on the package and applies a voltage to one electrode of the light emitting diode, and supplies a current flowing at the time of screening the light emitting diode to the other electrode of the light emitting diode, arranged on the package. An optical transmitter, comprising: a light-emitting diode selecting current supply terminal for use in the method. 2. A light emitting diode, a driving circuit connected between two electrodes of an anode and a cathode of the light emitting diode for driving the light emitting diode to output an optical signal, and mounting the light emitting diode and the driving circuit A voltage applying terminal for a light emitting diode, which is arranged on the package and applies a voltage to one electrode of the light emitting diode, and supplies a current flowing at the time of screening the light emitting diode to the other electrode of the light emitting diode, arranged on the package. And a switch for electrically turning on and off between the light-emitting diode selecting current supply terminal and the other electrode of the light-emitting diode. Transmitter. 3. The optical transmitter according to claim 1, wherein the light-emitting diode selecting current supply terminal is disposed on a rear surface of the package so as not to protrude from a side surface. 4. The optical transmitter according to claim 1, wherein the one electrode is a cathode and the other electrode is an anode. 5. A predetermined current larger than that in normal use is supplied from a constant current source to the light emitting diode selection current supply terminal while the package is heated to a predetermined temperature in a thermostat. The optical transmitter according to claim 1 or 2, wherein: 6. A current supply terminal for selecting a light emitting diode, wherein a predetermined current larger than that in normal use is supplied from a constant current source in a state where the package is heated to a predetermined temperature in a constant temperature bath. And a control circuit for controlling the temperature of the constant temperature chamber, controlling the current of the constant current source, and controlling the application of the constant voltage to the voltage application terminal for the light emitting diode. The optical transmitter according to claim 1.